JP2018120153A - Zoom lens and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens achieving reduction in size and weight and high optical performance, and an imaging device including the zoom lens.SOLUTION: The zoom lens comprises, successively from an object side, a positive first lens group G1 that is immobile upon varying magnifications, at least two movable lens groups that move upon varying magnifications, and a positive final lens group that is immobile upon varying magnifications. The final lens group comprises, successively from the object side, a front group Gf and a rear group Gr. The front group Gf has, successively from the side closest to the object side, at most two positive lenses and a single front group first negative lens in a continued state, and on the side closest to the image side, has a front group second negative lens having a concave surface on the image side, different from the front group first negative lens. The zoom lens has an aperture stop St between the movable lens group and the front group first negative lens. The rear group Gr comprises a positive lens and a rear group negative meniscus lens having a convex surface on the image side. The zoom lens satisfies a predetermined conditional expression.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a zoom lens suitable for an electronic camera such as a movie shooting camera, a broadcast camera, a digital camera, a video camera, and a surveillance camera, and an imaging apparatus including the zoom lens.

  As a zoom lens used in electronic cameras such as a movie camera, a broadcast camera, a digital camera, a video camera, and a surveillance camera, a zoom lens disclosed in Patent Document 1 below has been proposed.

JP 09-243916 A

  A zoom lens having good optical performance is demanded for an imaging apparatus such as a movie camera and a broadcast camera while being small and lightweight. In particular, there is a strong demand for a reduction in size and weight for an imaging mode that places emphasis on mobility and operability.

  However, when the size and weight are reduced, spherical aberration and curvature of field increase, and it becomes difficult to achieve sufficient optical performance. The lens system described in Patent Document 1 does not have a sufficiently small spherical aberration with respect to a level requested in recent years.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a zoom lens in which downsizing and weight reduction are achieved and high optical performance is realized, and an imaging apparatus including the zoom lens. .

In the zoom lens of the present invention, in order from the object side, the distance in the optical axis direction between the first lens group having a positive refractive power fixed to the image plane at the time of zooming and the adjacent group at the time of zooming is changed. At least two moving lens groups that move in parallel, and a final lens group having a positive refractive power that is fixed with respect to the image plane at the time of zooming. The final lens group includes, in order from the object side, the front group and the front group Is composed of a rear group separated by an air gap, and the front group has two or less positive lenses and one front group first negative lens successively in order from the most object side, A front group second negative lens having a concave surface facing the image side, which is different from the front group first negative lens, has a stop between the moving lens group and the front group first negative lens, and the rear group has a positive And a rear group negative meniscus lens having a convex surface facing the image side, and the front group from the image side surface of the front group first negative lens. The distance on the optical axis to the image-side surface of the second negative lens D1n, when a distance on the optical axis from the most object side surface of the front group to the surface of the most image-side was D1,
0.1 <D1n / D1 <1 (1)
It satisfies the conditional expression (1) expressed by:

In addition,
0.3 <D1n / D1 <0.8 (1-1)
0.5 <D1n / D1 <0.7 (1-2)
It is preferable that the conditional expression (1-1) and / or (1-2) represented by

In the zoom lens of the present invention, when the focal length of the second negative lens in the front group is fL1n2, and the focal length of the negative meniscus lens in the rear group is fL2n,
0.1 <fL1n2 / fL2n <1 (2)
It is preferable that the conditional expression (2) represented by
0.1 <fL1n2 / fL2n <0.5 (2-1)
0.1 <fL1n2 / fL2n <0.3 (2-2)
It is preferable that the conditional expression (2-1) and / or (2-2) represented by

When the focal length of the last lens group is fR and the focal length of the front group is fR1,
0.1 <fR / fR1 <2 (3)
It is preferable that the conditional expression (3) represented by
0.2 <fR / fR1 <1.5 (3-1)
It is preferable that the conditional expression (3-1) represented by these is satisfied.

Further, when the curvature radius of the image side surface of the rear group negative meniscus lens is r2n2, and the curvature radius of the object side surface of the rear group negative meniscus lens is r2n1,
0.1 <(r2n2-r2n1) / (r2n2 + r2n1) <1 (4)
It is preferable that the conditional expression (4) represented by
0.1 <(r2n2-r2n1) / (r2n2 + r2n1) <0.5 (4-1)
0.1 <(r2n2-r2n1) / (r2n2 + r2n1) <0.4 (4-2)
It is preferable that the conditional expression (4-1) and / or (4-2) represented by

  Further, the rear group may be composed of a positive lens and a rear group negative meniscus lens in order from the object side, or may be composed of a rear group negative meniscus lens and a positive lens in order from the object side. .

  In addition, the front group may include, in order from the object side, a positive lens, a positive lens, a front group first negative lens, a positive lens, a positive lens, and a front group second negative lens. In order from the object side, a positive lens, a front group first negative lens, a positive lens, a positive lens, and a front group second negative lens may be included.

  The at least two moving lens groups may be composed of two moving lens groups. In this case, the at least two moving lens groups are second lens groups having negative refractive power in order from the object side. And a third lens group having a positive refractive power.

  Further, the at least two moving lens groups may be composed of three moving lens groups. In this case, the at least two moving lens groups are second lens groups having positive refractive power in order from the object side. And a third lens group having a negative refractive power and a fourth lens group having a negative refractive power.

  An image pickup apparatus according to the present invention includes the zoom lens according to the present invention described above.

  The above “consisting of” means a lens having substantially no power other than those listed as constituent elements, an optical element other than a lens such as an aperture, a mask, a cover glass, and a filter, a lens flange, and a lens. It is intended that a mechanical part such as a barrel, an image sensor, a camera shake correction mechanism, and the like may be included.

  In addition, the surface shape of the lens, the sign of refractive power, and the radius of curvature are considered in the paraxial region when an aspheric surface is included.

In the zoom lens of the present invention, in order from the object side, the distance in the optical axis direction between the first lens group having a positive refractive power fixed to the image plane at the time of zooming and the adjacent group at the time of zooming is changed. At least two moving lens groups that move in parallel, and a final lens group having a positive refractive power that is fixed with respect to the image plane at the time of zooming. The final lens group includes, in order from the object side, the front group and the front group Is composed of a rear group separated by an air gap, and the front group has two or less positive lenses and one front group first negative lens successively in order from the most object side, A front group second negative lens having a concave surface facing the image side, which is different from the front group first negative lens, has a stop between the moving lens group and the front group first negative lens, and the rear group has a positive And a rear group negative meniscus lens having a convex surface facing the image side, and the front group from the image side surface of the front group first negative lens. 2 When the distance on the optical axis to the image side surface of the negative lens is D1n and the distance on the optical axis from the most object side surface to the most image side surface of the front group is D1, the following conditional expression (1 Therefore, it is possible to provide a zoom lens in which miniaturization and weight reduction are achieved and high optical performance is realized, and an imaging device including the zoom lens.
0.1 <D1n / D1 <1 (1)

Sectional drawing which shows the lens structure of the zoom lens (common to Example 1) concerning one Embodiment of this invention. Sectional drawing which shows the lens structure of the zoom lens of Example 2 of this invention. Sectional drawing which shows the lens structure of the zoom lens of Example 3 of this invention. Sectional drawing which shows the lens structure of the zoom lens of Example 4 of this invention. Each aberration diagram of the zoom lens of Example 1 of the present invention Each aberration diagram of the zoom lens of Example 2 of the present invention Each aberration diagram of the zoom lens of Example 3 of the present invention Each aberration diagram of the zoom lens of Example 4 of the present invention 1 is a schematic configuration diagram of an imaging apparatus according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a lens configuration of a zoom lens according to an embodiment of the present invention and a sectional view of an optical path. In FIG. 1, the wide-angle end state is shown in the upper stage, the axial light beam wa and the light flux wb with the maximum field angle are entered as the light flux, and the telephoto end state is shown in the lower stage, and the axial light flux ta and the light flux tb with the maximum field angle are used as the light flux. Further, the movement locus of the moving lens group is indicated by an arrow. The example shown in FIG. 1 corresponds to a zoom lens of Example 1 described later. In FIG. 1, the left side of the drawing is the object side, and the right side of the drawing is the image side, showing a state where the object is focused on an object at infinity. Further, the illustrated aperture stop St does not necessarily indicate the size or shape, but indicates the position on the optical axis Z.

  When the zoom lens is mounted on the image pickup apparatus, it is preferable to include various filters and / or protective cover glasses according to the specifications of the image pickup apparatus. The optical member PP is arranged between the lens system and the image plane Sim. However, the position of the optical member PP is not limited to that shown in FIG. 1, and a configuration in which the optical member PP is omitted is also possible.

  In the zoom lens according to the present embodiment, in order from the object side, the distance in the optical axis direction between the first lens group G1 having a positive refractive power fixed with respect to the image plane Sim at the time of zooming and the adjacent group at the time of zooming. And at least two moving lens groups that move while changing, and a final lens group having a positive refractive power that is fixed with respect to the image plane Sim at the time of zooming. In the present embodiment, the second lens group G2 and the third lens group G3 correspond to a moving lens group, and the fourth lens group G4 corresponds to a final lens group.

  In this way, the entire lens system can be shortened by using the first lens group G1 closest to the object side as a lens group having a positive refractive power. Further, by fixing the most object side first lens group G1 at the time of zooming, it is possible to prevent the entire lens length from changing at the time of zooming. Further, by making the final lens group closest to the image side a lens group having a positive refractive power, it is possible to suppress an increase in the incident angle of the principal ray of the off-axis ray to the image plane Sim. Can be suppressed.

  The final lens group (fourth lens group G4 in the present embodiment) is composed of, in order from the object side, the front group Gf and the rear group Gr separated from the front group Gf by the air group. In order from the object side, two or less positive lenses and one front group first negative lens (in this embodiment, a lens L43) are successively provided, and are most different from the front group first negative lens on the image side. A front group second negative lens (lens L46 in this embodiment) having a concave surface facing the image side, an aperture stop St between the moving lens group and the front group first negative lens, and a rear group Gr Consists of a positive lens and a rear group negative meniscus lens (lens L48 in this embodiment) with the convex surface facing the image side.

  Thus, by arranging the positive lens closest to the object side of the front group Gf, the effective diameter of the final lens group is prevented from becoming too large, and the front group second negative lens is arranged closest to the image side of the front group Gf. By doing so, the total length can be shortened. In addition, by suppressing the number of positive lenses continuously arranged in order from the most object side of the front group Gf to two or less, it is possible to prevent the thickness on the optical axis of the front group Gf from becoming too thick. In addition, the front-group second negative lens can correct low-order spherical aberration while suppressing generation of high-order spherical aberration by directing a concave surface toward the image side. The positive lens in the rear group Gr is responsible for correcting the distortion and lateral chromatic aberration generated in the second negative lens in the front group, and the rear group negative meniscus lens is curved in the field while suppressing the generation of astigmatism. Responsible for correcting.

Further, in the zoom lens according to the present embodiment, the distance on the optical axis from the image side surface of the front group first negative lens to the image side surface of the front group second negative lens is D1n, and the most object side of the front group When the distance on the optical axis from the surface to the surface closest to the image side is D1, the following conditional expression (1) is satisfied. By making it not exceed the upper limit of conditional expression (1), the total length of the lens system can be suppressed. By avoiding being less than or equal to the lower limit of conditional expression (1), the front group first negative lens close to the aperture stop St and the front group second negative lens far from the aperture stop St can be arranged apart from each other. Since the chief ray passing through the second negative lens is higher than the chief ray passing through the first negative lens in the front group, axial chromatic aberration mainly in the front group first negative lens, and axial chromatic aberration and magnification chromatic aberration in the front group second negative lens. Can be corrected, and it becomes easy to change the balance between longitudinal chromatic aberration and lateral chromatic aberration. If the following conditional expression (1-1) and / or (1-2) is satisfied, better characteristics can be obtained.
0.1 <D1n / D1 <1 (1)
0.3 <D1n / D1 <0.8 (1-1)
0.5 <D1n / D1 <0.7 (1-2)

In the zoom lens according to the present embodiment, it is preferable that the following conditional expression (2) is satisfied when the focal length of the second negative lens in the front group is fL1n2 and the focal length of the negative meniscus lens in the rear group is fL2n. By making it not exceed the upper limit of conditional expression (2), it is possible to suppress the refractive power of the rear group negative meniscus lens from becoming too strong, so that the occurrence of distortion and lateral chromatic aberration can be suppressed. By making it not below the lower limit of conditional expression (2), it is possible to prevent the refractive power of the second negative lens in the front group from becoming too strong, so that the occurrence of astigmatism can be suppressed. Furthermore, since the refractive power of the rear group negative meniscus lens can be increased, the field curvature can be sufficiently corrected. If the following conditional expressions (2-1) and / or (2-2) are satisfied, better characteristics can be obtained.
0.1 <fL1n2 / fL2n <1 (2)
0.1 <fL1n2 / fL2n <0.5 (2-1)
0.1 <fL1n2 / fL2n <0.3 (2-2)

Further, it is preferable that the following conditional expression (3) is satisfied, where fR is the focal length of the final lens group and fR1 is the focal length of the front group. By making it not to exceed the upper limit of conditional expression (3), it is possible to suppress the refractive power of the front group Gf from becoming too strong, and it becomes easy to correct spherical aberration. By making it not to be below the lower limit of conditional expression (3), it is possible to suppress the refractive power of the front group Gf from becoming too weak, so that the overall length can be suppressed. If the following conditional expression (3-1) is satisfied, better characteristics can be obtained.
0.1 <fR / fR1 <2 (3)
0.2 <fR / fR1 <1.5 (3-1)

Further, when the radius of curvature of the image side surface of the rear group negative meniscus lens is r2n2, and the radius of curvature of the object side surface of the rear group negative meniscus lens is r2n1, it is preferable that the following conditional expression (4) is satisfied. The occurrence of astigmatism can be suppressed by preventing the conditional expression (4) from exceeding the upper limit. By preventing the lower limit of conditional expression (4) from being reached, the occurrence of higher-order spherical aberration can be suppressed. If the following conditional expressions (4-1) and / or (4-2) are satisfied, better characteristics can be obtained.
0.1 <(r2n2-r2n1) / (r2n2 + r2n1) <1 (4)
0.1 <(r2n2-r2n1) / (r2n2 + r2n1) <0.5 (4-1)
0.1 <(r2n2-r2n1) / (r2n2 + r2n1) <0.4 (4-2)

  Further, the rear group Gr may be composed of a positive lens and a rear group negative meniscus lens in order from the object side. Such a configuration is advantageous for correction of field curvature.

  Further, the rear group Gr may be composed of a rear group negative meniscus lens and a positive lens in order from the object side. Such a configuration is advantageous for correcting distortion.

  The front group Gf may include a positive lens, a positive lens, a front group first negative lens, a positive lens, a positive lens, and a front group second negative lens in order from the object side. With such a configuration, it is possible to suppress the overall length while suppressing the occurrence of spherical aberration.

  The front group Gf may include a positive lens, a front group first negative lens, a positive lens, a positive lens, and a front group second negative lens in order from the object side. With such a configuration, it is possible to suppress the occurrence of spherical aberration while suppressing the thickness of the front group Gf on the optical axis.

  The at least two moving lens groups may be composed of two moving lens groups. With such a configuration, the overall length of the entire lens system can be suppressed.

  In such a configuration, the at least two moving lens groups include, in order from the object side, the second lens group G2 having a negative refractive power and the third lens group G3 having a positive refractive power. It may be a thing. This configuration corresponds to Examples 1, 2, and 3 (FIGS. 1, 2, and 3) described later. The moving locus of the moving lens group is entered only in Example 1 (FIG. 1) and omitted in the other Examples 2 and 3 (FIGS. 2 and 3). The same applies to 1, 2, and 3. Thus, by making the refractive power of the third lens group G3 positive, the off-axis ray height can be lowered, so the outer diameter of the first lens group G1 can be reduced, and the size and size can be reduced. The lens configuration is advantageous for weight reduction. Furthermore, the incident angle to the fourth lens group G4 can be suppressed, and spherical aberration can be reduced over the entire zoom range.

  The at least two moving lens groups may be composed of three moving lens groups. With such a configuration, it is possible to achieve good optical characteristics while suppressing the overall length of the entire lens system.

  In such a configuration, the at least two moving lens groups include, in order from the object side, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a negative lens power. The fourth lens group G4 having a refractive power of 5 may be used. This configuration corresponds to Example 4 (FIG. 4) described later. Thus, by making the refractive power of the second lens group G2 positive, the off-axis ray height can be lowered, so that the outer diameter of the first lens group G1 can be reduced, and the size and size can be reduced. The lens configuration is advantageous for weight reduction. Furthermore, since the movement range of the third lens group G3 and the movement range of the fourth lens group G4 can be overlapped, the overall length can be shortened.

  In the example shown in FIG. 1, an example in which the optical member PP is disposed between the lens system and the image plane Sim is shown. However, a low-pass filter, various filters that cut a specific wavelength range, and the like are used as the lens system. These various filters may be arranged between the lenses instead of being arranged between the image plane Sim, or the lens surface of any lens is coated with a coating having the same action as the various filters. May be.

Next, numerical examples of the zoom lens according to the present invention will be described.
First, the zoom lens of Example 1 will be described. FIG. 1 is a sectional view showing the lens configuration of the zoom lens of Example 1. As shown in FIG. In FIG. 1 and FIGS. 2 to 4 corresponding to Examples 2 to 4 to be described later, the wide-angle end state is shown in the upper stage, the axial light beam wa and the light beam wb with the maximum field angle are entered as the light beams, and the telephoto end state in the lower stage. The on-axis light beam ta and the light beam tb with the maximum field angle are entered as light beams, and the movement locus of the moving lens group is indicated by an arrow. Further, the left side of the drawing is the object side, and the right side of the drawing is the image side, which shows a state in which the object at infinity is focused. Further, the illustrated aperture stop St does not necessarily indicate the size or shape, but indicates the position on the optical axis Z.

  The zoom lens of Example 1 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power. And a fourth lens group G4 having a positive refractive power. In this embodiment, the second lens group G2 and the third lens group G3 correspond to a moving lens group, and the fourth lens group G4 corresponds to a final lens group.

  The first lens group G1 includes seven lenses L11 to L17, the second lens group G2 includes four lenses L21 to L24, and the third lens group G3 includes lenses L31 to L24. The fourth lens group G4 is composed of eight lenses L41 to L48.

  The fourth lens group G4 (final lens group) includes a front group Gf including six lenses L41 to L46, and a rear group Gr including two lenses L47 and L48.

  Table 1 shows basic lens data of the zoom lens of Example 1, Table 2 shows data on specifications, and Table 3 shows data on changing surface distance. In the following, the meaning of the symbols in the table will be described using the example 1 as an example, but the same applies to the examples 2 to 4.

  In the lens data of Table 1, the surface number column indicates the surface number that increases sequentially toward the image surface side with the surface of the component closest to the object side as the first, and the curvature radius column indicates the curvature radius of each surface. In the surface interval column, an interval on the optical axis Z between each surface and the next surface is shown. The column of n shows the refractive index of each optical element at the d-line (wavelength 587.6 nm (nanometer)), and the column of ν shows the d-line of each optical element (wavelength 587.6 nm (nanometer)). Indicates the Abbe number at.

  Here, the sign of the radius of curvature is positive when the surface shape is convex toward the object side, and negative when the surface shape is convex toward the image surface side. The basic lens data includes the aperture stop St and the optical member PP. In the surface number column of the surface corresponding to the aperture stop St, the phrase (aperture) is written together with the surface number. Further, in the lens data of Table 1, DD [surface number] is described in each of the surface interval columns in which the interval changes upon zooming. Table 3 shows numerical values corresponding to the DD [surface number].

  The data relating to the specifications in Table 2 includes zoom magnification, focal length f ′, back focus Bf ′, F number FNo. The value of the total field angle 2ω is shown.

  In basic lens data, data on specifications, and data on changing surface spacing, degrees are used as the unit of angle, and mm (millimeter) is used as the unit of length, but the optical system is proportionally enlarged or proportional. Other suitable units can also be used because they can be used even when reduced.

  Each aberration diagram of the zoom lens of Example 1 is shown in FIG. 5 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the wide-angle end in order from the upper left side in FIG. 5, and spherical aberration, astigmatism, distortion at the telephoto end in order from the lower left side in FIG. Aberration and lateral chromatic aberration are shown. These aberration diagrams show states when the object distance is infinite. Each aberration diagram showing spherical aberration, astigmatism, and distortion aberration shows aberration with the d-line (wavelength 587.6 nm (nanometer)) as a reference wavelength. The spherical aberration diagram includes d line (wavelength 587.6 nm (nanometer)), C line (wavelength 656.3 nm (nanometer)), F line (wavelength 486.1 nm (nanometer)), and g line (wavelength 435). The aberrations for .8 nm (nanometers) are indicated by solid lines, long broken lines, short broken lines, and gray solid lines, respectively. In the astigmatism diagram, the sagittal and tangential aberrations are indicated by a solid line and a short broken line, respectively. The lateral chromatic aberration diagram shows the aberrations for the C-line (wavelength 656.3 nm (nanometer)), F-line (wavelength 486.1 nm (nanometer)), and g-line (wavelength 435.8 nm (nanometer)), respectively. Indicated by a dashed line, a short dashed line, and a solid gray line. In addition, FNo. Means F number, and ω in other aberration diagrams means half angle of view.

  Next, a zoom lens of Example 2 will be described. FIG. 2 is a sectional view showing the lens configuration of the zoom lens of Example 2. As shown in FIG. Compared with the zoom lens of Example 1, the zoom lens of Example 2 includes the front lens group Gf, in which the fourth lens group G4 is composed of five lenses L41 to L45, and two lenses L46 and L47. Except for the rear group Gr, the refractive power configuration of each group and the lens number configuration of each group are the same. In addition, Table 4 shows basic lens data of the zoom lens of Example 2, Table 5 shows data on specifications, Table 6 shows data on changing surface distance, and FIG. 6 shows aberration diagrams.

  Next, a zoom lens according to Example 3 will be described. FIG. 3 is a cross-sectional view showing the lens configuration of the zoom lens of Example 3. In the zoom lens according to the third embodiment, the refractive power configuration in each group and the number of lenses in each group are the same as those in the first embodiment. Further, basic lens data of the zoom lens of Example 3 is shown in Table 7, data relating to the specifications is shown in Table 8, data relating to the changing surface distance is shown in Table 9, and each aberration diagram is shown in FIG.

  Next, a zoom lens according to Example 4 will be described. FIG. 4 is a cross-sectional view showing the lens configuration of the zoom lens of Example 4.

  The zoom lens of Example 4 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power. And a fourth lens group G4 having a negative refractive power and a fifth lens group G5 having a positive refractive power. In this embodiment, the second lens group G2, the third lens group G3, and the fourth lens group G4 correspond to a moving lens group, and the fifth lens group G5 corresponds to a final lens group.

  The first lens group G1 includes seven lenses L11 to L17, the second lens group G2 includes only one lens L21, and the third lens group G3 includes lenses L31 to L34. The fourth lens group G4 includes two lenses L41 and L42, and the fifth lens group G5 includes eight lenses L51 to L58.

  The fifth lens group G5 (final lens group) includes a front group Gf including six lenses L51 to L56 and a rear group Gr including two lenses L57 and L58.

  In addition, Table 10 shows basic lens data of the zoom lens of Example 4, Table 11 shows data on specifications, Table 12 shows data on changing surface distance, and FIG. 8 shows aberration diagrams.

  Table 13 shows values corresponding to the conditional expressions (1) to (4) of the zoom lenses of Examples 1 to 4. In all examples, the d-line is used as the reference wavelength, and the values shown in Table 13 below are at this reference wavelength.

  From the above data, all of the zoom lenses of Examples 1 to 4 satisfy the conditional expressions (1) to (4), which is a zoom lens that achieves miniaturization and weight reduction and high optical performance. I understand that.

  Next, an imaging apparatus according to an embodiment of the present invention will be described. FIG. 9 shows a schematic configuration diagram of an imaging apparatus 10 using the zoom lens 1 according to the embodiment of the present invention as an example of the imaging apparatus of the embodiment of the present invention. Examples of the imaging device 10 include a movie camera, a broadcast camera, a digital camera, a video camera, and a surveillance camera.

  The imaging device 10 includes a zoom lens 1, a filter 2 disposed on the image side of the zoom lens 1, and an imaging element 3 disposed on the image side of the filter 2. In FIG. 9, the first lens group G1 to the fourth lens group G4 included in the zoom lens 1 are schematically illustrated. The first lens group G1 is divided into three sub-lens groups, a first-a lens group G1a, a first-b lens group G1b, and a first-c lens group G1c, which are also schematically shown.

  The image sensor 3 converts an optical image formed by the zoom lens 1 into an electrical signal, and for example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) can be used. The image sensor 3 is arranged such that its image plane coincides with the image plane of the zoom lens 1.

  The imaging device 10 also includes a signal processing unit 5 that performs arithmetic processing on an output signal from the imaging device 3, a display unit 6 that displays an image formed by the signal processing unit 5, and a zoom that controls zooming of the zoom lens 1. A control unit 7 and a focus control unit 8 that controls focusing of the zoom lens 1 are provided. Although only one image sensor 3 is shown in FIG. 9, the image pickup apparatus of the present invention is not limited to this, and may be a so-called three-plate type image pickup apparatus having three image pickup elements.

  The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, the radius of curvature, the surface spacing, the refractive index, and the Abbe number of each lens are not limited to the values shown in the above numerical examples, and can take other values.

DESCRIPTION OF SYMBOLS 1 Zoom lens 2 Filter 3 Image pick-up element 5 Signal processing part 6 Display part 7 Zoom control part 8 Focus control part 10 Imaging device G1 1st lens group G1a 1a lens group G1b 1b lens group G1c 1c lens group G2 2nd lens Group G3 Third lens group G4 Fourth lens group G5 Fifth lens group Gf Front group Gr Rear group L11-L58 Lens PP Optical member Sim Image surface St Aperture stop ta, wa On-axis light beam tb, wb Light beam with maximum field angle Z optical axis

Claims (20)

In order from the object side, at least two movements that change the distance in the optical axis direction between the first lens group having a positive refractive power that is fixed with respect to the image plane at the time of zooming and the adjacent group at the time of zooming. A lens group and a final lens group having a positive refractive power that is fixed with respect to the image plane at the time of zooming,
The final lens group, in order from the object side, consists of a front group and the rear group separated from the front group by an air interval;
The front group has two or less positive lenses and one front group first negative lens successively in order from the most object side, and is different from the front group first negative lens on the most image side. A front group second negative lens with a concave surface facing
A diaphragm between the moving lens group and the front group first negative lens;
The rear group consists of a positive lens and a rear group negative meniscus lens having a convex surface facing the image side,
The distance on the optical axis from the image side surface of the front group first negative lens to the image side surface of the front group second negative lens is D1n, the most object side surface to the most image side surface of the front group When the distance on the optical axis to D1 is
0.1 <D1n / D1 <1 (1)
A zoom lens characterized by satisfying conditional expression (1) expressed by: When the focal length of the front group second negative lens is fL1n2, and the focal length of the rear group negative meniscus lens is fL2n,
0.1 <fL1n2 / fL2n <1 (2)
The zoom lens according to claim 1, satisfying conditional expression (2) expressed by: When the focal length of the last lens group is fR and the focal length of the front group is fR1,
0.1 <fR / fR1 <2 (3)
The zoom lens according to claim 1, wherein a conditional expression (3) represented by: When the radius of curvature of the image side surface of the rear group negative meniscus lens is r2n2, and the radius of curvature of the object side surface of the rear group negative meniscus lens is r2n1,
0.1 <(r2n2-r2n1) / (r2n2 + r2n1) <1 (4)
The zoom lens according to any one of claims 1 to 3, wherein a conditional expression (4) represented by: The zoom lens according to claim 1, wherein the rear group includes a positive lens and the rear group negative meniscus lens in order from the object side. The zoom lens according to any one of claims 1 to 4, wherein the rear group includes the rear group negative meniscus lens and a positive lens in order from the object side. The front group includes, in order from the object side, a positive lens, a positive lens, the front group first negative lens, a positive lens, a positive lens, and the front group second negative lens. The zoom lens according to any one of the above. The front group includes, in order from the object side, a positive lens, the front group first negative lens, a positive lens, a positive lens, and the front group second negative lens. Zoom lens described in the item. The zoom lens according to any one of claims 1 to 8, wherein the at least two moving lens groups include two moving lens groups. The zoom lens according to claim 9, wherein the at least two moving lens groups include, in order from the object side, a second lens group having a negative refractive power and a third lens group having a positive refractive power. The zoom lens according to any one of claims 1 to 8, wherein the at least two moving lens groups include three moving lens groups. The at least two moving lens groups include, in order from the object side, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens group having a negative refractive power. The zoom lens according to claim 11. 0.3 <D1n / D1 <0.8 (1-1)
The zoom lens according to claim 1, wherein a conditional expression (1-1) represented by: 0.5 <D1n / D1 <0.7 (1-2)
The zoom lens according to claim 1, wherein a conditional expression (1-2) expressed by: 0.1 <fL1n2 / fL2n <0.5 (2-1)
The zoom lens according to claim 2, satisfying conditional expression (2-1) expressed by: 0.1 <fL1n2 / fL2n <0.3 (2-2)
The zoom lens according to claim 2, satisfying conditional expression (2-2) expressed by: 0.2 <fR / fR1 <1.5 (3-1)
The zoom lens according to claim 3, wherein conditional expression (3-1) represented by: 0.1 <(r2n2-r2n1) / (r2n2 + r2n1) <0.5 (4-1)
The zoom lens according to claim 4, wherein a conditional expression (4-1) expressed by: 0.1 <(r2n2-r2n1) / (r2n2 + r2n1) <0.4 (4-2)
The zoom lens according to claim 4, satisfying conditional expression (4-2) expressed by:   An image pickup apparatus comprising the zoom lens according to any one of claims 1 to 19.